Responses to Abiotic Factors

Every living organism must respond, in some way, to changes in its abiotic environment, and the chapter recognises four broad response strategies. Regulators maintain a constant internal physiological state — steady body temperature, or steady ionic and osmotic balance — through active physiological means; this ability is chiefly seen in birds, mammals, and a few lower vertebrate and invertebrate species capable of true homeostasis. Conformers, by contrast, cannot maintain a constant internal state, so their body conditions simply track the ambient environment — for instance, many aquatic animals such as fish have body-fluid osmotic concentration that rises and falls with the osmotic concentration of the surrounding water. Migrators move temporarily away from a stressful habitat to a more hospitable area and return once the stress has passed — Siberian cranes, for example, migrate from Siberia to Vedanthangal in Tamil Nadu to escape severe winters before returning home in spring. Finally, organisms that can neither regulate nor migrate may instead suspend activity altogether: bears go into hibernation through winter, some snails and fish go into aestivation to avoid summer heat and desiccation, and some lower animals suspend a specific de …